1. Field of the Invention
The present invention relates to a liquid droplet jetting apparatus which jets liquid droplets of a liquid.
2. Description of the Related Art
As a liquid droplet jetting apparatus which jets liquid droplets from nozzles, an ink-jet printer which includes an ink-jet head which jets droplets of an ink onto a recording paper has hitherto been known. In such an ink-jet printer, due to entry of an air bubble into an ink channel or due to increase in the viscosity (due to thickening) of the ink inside the nozzle caused by the drying of the ink, nozzle jetting failure occurs in some cases. To address this situation, an ink-jet recording apparatus of general type is provided with a unit or device which discharges the air bubble and/or the thickened ink inside the ink channel to thereby recover the jetting performance of the nozzles.
The applicant of the present patent application has proposed an ink-jet printer capable of performing (carrying out) a suction purge in which air bubbles and/or thickened ink are forcibly discharged by suction (suction-discharged) from a nozzle positioned at a terminal end portion of the ink channel, and an air discharge purge in which the air bubble is suction-discharged from a portion of the ink channel located at an upstream side of the nozzle. For example, a certain ink-jet printer includes, as the construction for the suction purge, a nozzle cap which closes a jetting port of the nozzle by making a tight or close contact with a liquid droplet jetting surface of an ink-jet head. In addition, the ink-jet printer includes, as the structure for the air discharge purge, a buffer tank having an air bubble storage (accommodating) chamber which communicates with the ink-jet head, a discharge channel which is extended from the air bubble storage chamber, an opening/closing valve which opens and closes the discharge channel, and an air discharge cap which closes an end portion (a discharge port) of the discharge channel. Further, the nozzle cap and the air discharge cap are connected to the suction pump via a switching unit.
In the above-described ink-jet printer, by operating the suction pump in a state that the jetting port of the nozzle is closed by the nozzle cap, the ink including the thickened ink and/or air bubble is discharged by suction from the nozzle into the nozzle cap. On the other hand, by operating the suction pump in a state that the air discharge port of the discharge channel is closed by the air-discharge cap and that the discharge channel is opened by the opening/closing valve, air bubble in the air bubble storage chamber in the buffer tank positioned at the upstream side of the nozzle is discharged from the air bubble storage chamber to the air discharge cap via the discharge channel. By performing this air discharge purge, it is possible to reduce a suction time and a frequency of the suction purge performed for discharging the air bubble, thereby making it possible to suppress the ink consumption amount.